Conventionally, among rolling bearing apparatuses for supporting a drive roll in a continuous casting facility, there is an apparatus that has a housing which houses a rolling bearing and in which a water-cooling jacket is formed.
The water-cooling jacket is formed in a surface of the housing, which faces a slab side, and is formed of a recess portion that is indented radially inward from an outer peripheral surface of the housing, and a lid that, together with the recess portion, forms a space into which cooling water is introduced, by closing the recess portion. A water supply opening is formed in one end portion of the recess portion in a circumferential direction, and a water discharge opening is formed in the other end portion thereof in the circumferential direction. By introducing cooling water into the space through the water supply opening and discharging it from the water discharge opening, the housing is cooled to prevent heat radiated from a slab from being transferred to the rolling bearing (see, e.g., Patent Document 1).
Besides, there is also an apparatus as shown in FIG. 9 in which a recess portion 101 is formed on an outer peripheral surface of a housing 100 whose section is in a circular arc shape, and paired water supply openings 102 are formed in respective corner portions of the recess portion 101 that are at one end side of the recess portion 101 in a circumferential direction, and paired water discharge openings 103 are formed in respective corner portions of the recess portion 101 that are at the other end side of the recess portion 101 in the circumferential direction, and which is constructed such that the cooling water can be introduced evenly in the axial directions and the circumferential direction while a constant amount of flow is secured.
In the foregoing related-art rolling bearing apparatus, there are cases in which air bubbles occur and reside inside the water-cooling jacket. In particular, in the water-cooling jacket formed of the recess portion 101 as shown in FIG. 9, paired water discharge openings 103 for discharging the cooling water introduced through the two water supply openings 102 are formed in the respective corner portions of the recess portion 101, so that the jacket has a problem that there is a tendency that the cooling water resides in an intermediate portion positioned between the pair of water discharge openings 103 (a portion shown by an interrupted line in FIG. 9) and that air bubbles occur and reside in that portion. If such air bubbles form and reside inside the water-cooling jacket, the cooling efficiency of the water-cooling jacket declines. Besides, if the water discharge openings 103 are clogged from any cause, the residing air bubbles may expand due to radiation heat from a slab, thus leading to a possibility of breakage of the water-cooling jacket.
If, to overcome the problem, for example, the amount of water supplied through the water supply openings is increased to increase the amount of flow of cooling water in the jacket, it is possible to restrain the residence of the air bubbles; however, this is not favorable from the viewpoint of running cost, since the amount of water supplied increases.
In connection with the residence of air bubbles inside the water-cooling jacket as described above, there has been proposed an apparatus in which a rib protruded toward the inside of the water-cooling jacket is formed on the recess portion of the housing or an inner surface of the lid, the dimension of the rib in the axial direction is gradually narrowed from respective end portions of the water-cooling jacket in the circumferential direction toward a middle thereof and therefore sharp changes in the section of the water-cooling jacket are eliminated in a space between the pair of water supply openings provided in the end portion of the water-cooling jacket in the circumferential direction and the pair of water discharge openings provided in the other end portion so as to smooth the flow of the cooling water and therefore prevent the residence of air bubbles (e.g., see Patent Document 2).